Colonel Sir Benjamin Thompson, Count Rumford, FRS (26 March 1753 – 21 August 1814), was an American-born British military officer, scientist and inventor. Born in Woburn, Massachusetts, he supported the Loyalist cause during the American War of Independence, commanding the King's American Dragoons during the conflict. After the war ended in 1783, Thompson moved to London, where he was recognised for his administrative talents and received a knighthood from George III in 1784.
A prolific scientist and inventor, Thompson also created several new warship designs. He subsequently moved to the Electorate of Bavaria and entered into the employ of the Bavarian government, heavily reorganising the Bavarian Army. Thompson was rewarded for his efforts by being made an Imperial Count in 1792 before dying in Paris in 1814.
Thompson was born in rural Woburn, in the Province of Massachusetts Bay, on 26 March 1753; his birthplace is preserved as a museum. He was educated mainly at the village school, although he sometimes walked almost ten miles to Cambridge with the older Loammi Baldwin to attend lectures by Professor John Winthrop of Harvard College. At the age of 13 he was apprenticed to John Appleton, a merchant of nearby Salem. Thompson excelled at his trade, and coming in contact with refined and well educated people for the first time, adopted many of their characteristics including an interest in science. While recuperating in Woburn in 1769 from an injury, Thompson conducted his first experiments studying the nature of heat and began to correspond with Baldwin and others about them. Later that year he worked several months for a Boston shopkeeper and then apprenticed himself briefly, and unsuccessfully, to a doctor in Woburn.
Thompson's prospects were dim in 1772 but in that year they changed abruptly. He met, charmed and married a rich and well-connected widow, an heiress named Sarah Rolfe (née Walker). Her father was a minister, and her late husband left her property at Rumford, Province of New Hampshire, which is today in the modern city of Concord. They moved to Portsmouth, and through his wife's influence with the governor, he was appointed a major in the New Hampshire Militia. Their child (also named Sarah) was born in 1774.
Following the outbreak of the American Revolutionary War in 1775, Thompson, by now a wealthy and influential landowner, came out as a Loyalist. He was soon using his connections in the colonial militia to recruit and arm Loyalists seeking to fight alongside the British against rebel forces, which earned him the enmity of Patriots in New Hampshire. Thompson was stripped of his militia commission and a Patriot mob attacked and burned down his house, causing him to flee to British lines, abandoning his wife in the process. He became a political and military advisor to General Thomas Gage (to whom Thompson was already passing information on Patriots), and later assisted Lord George Germain in organizing and provisioning Loyalist military units.
In 1781, Thompson raised his own military unit, the King's American Dragoons, which was primarily stationed on Long Island in 1782 and early 1783, where they became notorious for demolishing a church and burial ground in order to erect Fort Golgotha in Huntington, New York.
"By 1775 Thompson had sailed for England, where under the auspices of the Secretary for the Colonies Lord George Germain he rose very rapidly in the service of the British government."
During his military career, Thompson conducted experiments to measure the force of gunpowder, the results of which were widely acclaimed when published in 1781 in the Philosophical Transactions of the Royal Society.
In 1779, he was elected a Fellow of the Royal Society In 1780 Thompson was appointed as Under-Secretary of the Northern Department in the British Government. But he left abruptly in the following year and traveled to North America as Lieutenant Colonel of the King's American Dragoons. When the American Revolutionary War came to an end, he returned to England and successfully applied to become full colonel. In 1783 he had a portrait painted of himself by Thomas Gainsborough, which is now on display in the Fogg Art Museum. On 23 February 1784, George III conferred upon him the honor of knighthood.
In 1799, the Royal Institution was founded as the result of a proposal by Thompson, for the "formation by Subscription, in the Metropolis of the British Empire, of a Public Institution for diffusing the Knowledge and facilitating the general Introduction of useful Mechanical Inventions and Improvements, and for the teaching by courses of Philosophical Lectures and Experiments, the application of Science to the Common Purposes of Life".
In 1785, he moved to Bavaria where he became an aide-de-camp to the Prince-elector Charles Theodore. He spent eleven years in Bavaria, reorganizing the army and establishing workhouses for the poor. He also invented Rumford's Soup, a soup for the poor, and established the cultivation of the potato in Bavaria. He studied methods of cooking, heating, and lighting, including the relative costs and efficiencies of wax candles, tallow candles, and oil lamps.
On Prince Charles' behalf he created the Englischer Garten in Munich in 1789; it remains today and is known as one of the largest urban public parks in the world. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1789.
For his efforts, in 1791 Thompson was made an Imperial Count, becoming Reichsgraf von Rumford. He took the name "Rumford" after the town of Rumford, New Hampshire, which was an older name for Concord where he had been married.
Benjamin Thompson has many claims on the interest of the historian of science. He founded the Royal Institution. His methods of conservation of heat and economy of fuel, his designs of stoves, fireplaces and cooking utensils were widely used during his lifetime. He was consulted on the laying out of kitchens in hospitals and institutions. He taught his contemporaries to recognise the fire built on an open hearth, the only means of domestic heating and cooking with which they were acquainted, for the ineffective and wasteful contrivance it really was. He held the most enlightened views, far in advance of his time, on the waste of fuel and the evils of atmospheric pollution in cities.
Rumford's constant preoccupation was the application of scientific principles to the improvement of the lot of the poor and the working classes, and it was in the subject of heat and its utilization that he found the greatest outlet for his endeavours.
His experiments on gunnery and explosives led to an interest in heat. He devised a method for measuring the specific heat of a solid substance but was disappointed when Johan Wilcke published his parallel discovery first.
Thompson next investigated the insulating properties of various materials, including fur, wool and feathers. He correctly deduced that the insulating properties of these natural materials arise from the fact that they inhibit the convection of air. He then inferred — incorrectly — that air and, in fact, all gases, were perfect non-conductors of heat. He further saw this as evidence of the argument from design, contending that divine providence had arranged for fur on animals in such a way as to guarantee their comfort.
In 1797, he extended his claim about non-conductivity to liquids. The idea raised considerable objections from the scientific establishment, John Dalton and John Leslie making particularly forthright attacks. Instrumentation far exceeding anything available in terms of accuracy and precision would have been needed to verify Thompson's claim. Again, he seems to have been influenced by his theological beliefs, and historian of science D. S. L. Cardwell speculated that Thompson wished to grant water a privileged and providential status in the regulation of human life.